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I did alot of googling on the subject of multiple GPUs. Both NVidia and ATI have presentations available, but all they give are guidelines on how to structure your rendering code to make AFR (alternate frame rendering) work efficiently.

My goal is quite different. I would like to perform standard rendering on GPU1, and at the same time, have compute shader code running on GPU2 (ie no AFR).

Does anyone have any pointers / links / advice on how I can test a setup like this? My current hardware configuration consists of 2 crossfired HD5750's.

Is this even possible through the DX11 API? If I were able to achieve this, would I even be able to share compute shader results from GPU2 to GPU1 without having to read results back to the CPU first?

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Hmm... true, that would do that job, though I was hoping for some way to share data between the GPUs through the crossfire / SLI bridge. That is unless there is a very fast way of getting the data to the other GPU without it?

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1) Crossfire the cards as normal. Do my compute shader stuff, followed by my rendering stuff in series (paying attention to guidelines given by ATI for alternate frame rendering)

2) Uncrossfire the cards. Create two separate D3D devices, one per card. Do all my compute stuff on one device, and all my rendering stuff on the other device. As soon as results become available from the compute device, upload to CPU, then load onto rendering GPU for use.

If you're curious, the "compute stuff" is a patch based radiosity solver. So while it doesn't NEED to be completely in sync with the rendering, it would certainly be more visually pleasing to see lighting updates as the light moves around, rather than having some delay in getting results.

I expect that 1) will give the most visually pleasing results, but the rendering might be bogged down if the solving step takes longer than theres room for. 2) would allow me to have the radiosity solved in a "separate thread" per se, independent of the rendering, which should make moving the camera around more snappy, but with delayed lighting results (which could turn out to be ok)

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:) this is exactly the project I'm doing. If you uncrossfire the cards, you can iterate through the adapter list, create one device on each card, then copy buffers between the two using UpdateSubresource(). You have to copy the UAV buffer to a readable buffer, and then read from that, and update the render GPU with the info that you get. If they are crossfired together, DirectX sees them as one adapter, and you don't have very much control over distribution between the two.

I managed to get the uncrossfire version working with a particle simulation, where you compute on one GPU and render on another GPU. on ATI, the performance boost wasn't very high, but with two NVIDIAs, you get a huge boost (probably because of the difference in memory speed).

I have the code snippet for copying the buffers between two devices posted here:

I would have liked it to be more "rounded" at the top, or a better spread instead of wasting [0], [1], [2] with values bellow 0.1.
Based on my experiments, the key to this is to provide a different sigma, but if I do, my kernel values no longer adds up to 1, which results to a darker blur.
I've found this post
... which helped me a bit, but I am really confused with this the part where he divide sigma by 3.
Can someone please explain how sigma works? How is it related to my kernel size, how can I balance my weights with different sigmas, ect...

Is it possible to asynchronously create a Texture2D using DirectX11?
I have a native Unity plugin that downloads 8K textures from a server and displays them to the user for a VR application. This works well, but there's a large frame drop when calling CreateTexture2D. To remedy this, I've tried creating a separate thread that creates the texture, but the frame drop is still present.
Is there anything else that I could do to prevent that frame drop from occuring?

I managed convert opengl code on http://john-chapman-graphics.blogspot.co.uk/2013/02/pseudo-lens-flare.html to hlsl, but unfortunately I don't know how to add it to my atmospheric scattering code (Sky - first image). Can anyone help me?
I tried to bind the sky texture as SRV and implement lens flare code in pixel shader, I don't know how to separate them (second image)

I have some code (not written by me) that is creating a window to draw stuff into using these:
CreateDXGIFactory1 to create an IDXGIFactory1
dxgi_factory->CreateSwapChain to create an IDXGISwapChain
D3D11CreateDevice to create an ID3D11Device and an ID3D11DeviceContext
Other code (that I dont quite understand) that creates various IDXGIAdapter1 and IDXGIOutput instances
Still other code (that I dont quite understand) that is creating some ID3D11RenderTargetView and ID3D11DepthStencilView instances and is doing something with those as well (possibly loading them into the graphics context somewhere although I cant quite see where)
What I want to do is to create a second window and draw stuff to that as well as to the main window (all drawing would happen on the one thread with all the drawing to the sub-window happening in one block and outside of any rendering being done to the main window). Do I need to create a second IDXGISwapChain for my new window? Do I need to create a second ID3D11Device or different IDXGIAdapter1 and IDXGIOutput interfaces? How do I tell Direct3D which window I want to render to? Are there particular d3d11 functions I should be looking for that are involved in this?
I am good with Direct3D9 but this is the first time I am working with Direct3D11 (and the guy who wrote the code has left our team so I cant ask him for help